You could, but you wouldn't get as high a rise. Once baking powder (the leavening in self-rising flour) meets liquid, it immediately starts creating carbon dioxide (which leavens the biscuits); the longer the dough sits the less leavening power it has. A better solution would be to prepare the dough up to the point of adding the liquid, refrigerate that, then add the liquid right before baking. It'll only add a couple minutes to your last-minute prep.